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GEITTT  or 
R,    Tracy  Crawford 


HOW  TO    IDENTIFY   THE   STARS 


THE  MACMILLAN  COMPANY 

NEW  YORK  •    BOSTON   •    CHICAGO 
ATLANTA  •    SAN   FRANCISCO 

MACMILLAN  &  (CO.,  LIMITED 

LONDON  '    BOMBAY  •    CALCUTTA 
MELBOURNE 

THE  MACMILLAN  CO.  OF  CANADA,  LTD, 

TORONTO 


HOW  TO   IDENTIFY 
THE  STARS 


BY 


WILLIS   I.    MILHAM,   PH.D. 

FIELD    MEMORIAL    PROFESSOR    OF    ASTRONOMY 
IN  WILLIAMS  COLLEGE 


THE   MACMILLAN   COMPANY 
1922 

All  rights  reserved 


COPYRIGHT,  1909, 
BY  THE  M ACMILLAN  COMPANY. 

Set  up  and  ciectrotyped      Published  June,  1909, 


ASTRONOMY  DEPT. 


Nottoood  $rrss 

J.  8.  Ctwhing  Co.  -  Berwick  fc  Smith  Oo. 
Norwood,  Mali.,  U.S.A. 


Mr 


CONTENTS 

»AGB 

I.    INTRODUCTION       .        T       .*       .        .     .  •.       .        i 

II.    THE  HISTORY  AND  NUMBER  OF  THE  CONSTELLA- 
TIONS       .       J*        .        .        ...        •        •        3 

III.  THE  METHODS  OF  DESIGNATING  A  STAR     .        .      12 

IV.  STAR  MAGNITUDES       .        ...        .        .15 

V.    STAR  COLORS        .        ...        .        .        .20 

VI.    THE  NUMBER  OF  THE  STARS       .        .        .        .21 

VII.    THE    METHOD    OF    LOCATING  THE    STARS  AND 

CONSTELLATIONS 23 

VIII.    THE  METHOD  OF  FURTHER  STUDY      ...      33 


M298751 


I.     INTRODUCTION 

THE  ability  to  recognize  the  more  brilliant 
stars  and  to  locate  the  more  conspicuous  con- 
stellations or  star  groups,  is  both  an  interest- 
ing and  a  useful  acquirement.  The  number  of 
people  who  have  a  real  interest  in  popular  as- 
tronomy and  a  fair  acquaintance  with  the  stars 
and  constellations  is  steadily  increasing  and 
they  find  real  pleasure  in  their  information.  To 
the  meteorologist  who  would  make  observa- 
tions of  the  position  of  the  streamers  of  the  Au- 
rora Borealis  or  locate  the  place  of  the  appear- 
ance and  disappearance  of  bright  meteors,  a 
knowledge  of  the  stars  and  constellations  is 
absolutely  necessary.  The  best  way  to  locate 
the  position  of  an  auroral  streamer  without  the 
use  of  apparatus  is  to  observe  the  stars  between 
which  and  over  which  it  extends.  Similarly  the 
point  of  appearance  and  disappearance  of  a  me> 
teor  has  been  definitely  determined  if  the  near- 
est star  in  each  case  has  been  noted.  If  great 


2  HOW  TO   IDENTIFY  THE   STARS 

exactness  is  desired,  the  angular  distance  and 
direction  of  the  point  in  question  from  the 
nearest  star  may  be  estimated.  Whenever  an 
object  is  thus  located  by  means  of  the  stars,  the 
exact  time  of  observation  and  the  place  of  ob- 
servation (latitude,  longitude,  and  elevation) 
must  also  be  stated.  From  such  observations 
made  at  two,  preferably  more,  stations,  the 
distance,  height,  and  direction  of  an  auroral 
display,  and  the  distance,  height,  direction  of 
motion,  velocity  of  motion,  and  orbit  in  space 
of  a  meteor  may  be  determined  by  computa- 
tion. 

The  purpose  of  the  constellation  tracings  and 
the  descriptive  material  here  given,  is  to  serve 
as  a  guide  in  taking  the  first  steps  in  learning 
the  stars  and  constellations  and  also  to  point 
the  way  to  the  acquisition  of  further  informa- 
tion on  the  part  of  those  who  desire  it.  The 
method  here  followed  and  the  material  presented 
is  essentially  the  same  as  that  used  in  the  course 
on  Descriptive  Astronomy  in  Williams  College. 


II.    THE   HISTORY   AND   NUMBER   OF 
THE  CONSTELLATIONS 

THE  first  definite  information  concerning  the 
constellations  comes  from  Claudius  Ptolemy  at 
the  Alexandrian  School  of  Philosophy  in  about 
150  A.D.  He  was  a  great  systematizer  of  in- 
formation and  summarized  the  astronomical 
learning  of  his  time.  His  original  writings  in 
the  Greek  are  lost,  but  an  Arabic  translation  of 
his  manuscript  on  Astronomy,  called  the  "Al- 
magest," has  come  down  to  us.  In  it  he  enu- 
merates, describes,  and  locates  48  constellations ; 
21  northern,  15  southern,  and  12  zodiacal. 
These  constellations  by  no  means  covered  the 
whole  sky,  as  a  large  part  of  the  southern  hemi- 
sphere was  not  mapped  and  there  were  often 
unmapped  spaces  between  the  constellations. 
As  the  centuries  passed,  the  need  of  more  con- 
stellations became  apparent,  but  it  was  consid- 
ered sacrilegious  to  add  to  the  Ptolemaic  list. 
Finally,  in  1601,  two  constellations  were  added 

3 


4  HOW  TO   IDENTIFY  THE   STARS 

by  Tycho  Brahe.  This  opened  the  way,  and  for 
two  centuries  nearly  every  astronomer  of  note 
considered  it  his  duty  to  map  a  group  of  stars 
and  give  to  the  group  a  name  of  his  own  choos- 
ing. Thus  by  1800  there  were  at  least  109 
fairly  well  known  constellations,  and  a  large  con- 
stellation (Argo)  in  the  southern  hemisphere 
was  divided  into  four,  thus  making  112.  The 
difficulties  were  now  as  great  as  before  new 
constellations  had  been  added,  for  some  of  the 
constellations  overlapped  and  names  had  been 
given  to  some  of  them  which  could  never  be- 
come international.  Gradually,  by  practically 
common  consent,  24  were  dropped,  so  that  at 
present  there  are  88  constellations.  The  ac- 
companying list  shows  the  number  of  constel- 
lations added  by  each  astronomer. 


HISTORY  OF  THE  CONSTELLATIONS  5 

140  A.D.     .         .         .     Ptolemy  ....         48 
1601  ,         .         .     Tycho  Brahe    ...  2 

1603  .         .         .     Bayer       ....         12 

1679  •  •  •  R°yer  •  •  •  5 

1690  .  .  .  Halley      .  ',',  .  .  i 

1690  .  .  .  Hevelius  .  ,  .  .  n 

1725  .  .  .  Flamsteed  .  .  .  2 

1752  .  .  .  LaCaille.  .  «  ».  14 

1770  .  .  Hell         .  .  .  .  i 

1776  .  .  .  Le  Monnier  .  .  •  2 

1776  •  ,.  .  Lalande  .  "v  .  .  i 

1777  .  .  .  Poczobut  .  .  .  i 
1800  .  .  .  Bode        ,  .  .  9 

109 
Argo  divided  into  four  parts  .  .  ,  .  3 

112 
Twenty-four  were  dropped  .  .  .  •  ^  24 

~88 

Some  authorities  attribute  one  constellation 
to  the  Emperor  Hadrian  in  130  A.D.,  one  to 
Eratosthenes  in  300  A.IX)  and  four  to  Bart- 
schius  in  1624  A.D.  and  thus  a  smaller  num- 
ber to  some  mentioned  in  the  table. 

These  eighty-eight  constellations  do  not 
overlap,  have  definite  boundaries,  and  cover 
the  whole  sky.  The  boundary  lines  usually 
wind  in  and  out  among  the  stars  and  are 
very  irregular,  particularly  in  the  case  of  the 


6  HOW  TO   IDENTIFY  THE   STARS 

northern  constellations.  Some  of  the  southern 
constellations  have  boundaries  which  are  for 
considerable  distances  arcs  of  great  or  small 
circles.  The  constellations  are  also  of  very 
unequal  size,  some  being  ten  times  as  large 
as  others. 

The  following  list  contains  the  names  of 
the  constellations,  the  Latin  genitive  of  the 
name,  the  meaning  of  the  name,  and  the 
name  of  the  originator  of  the  constellation :  — 


NAME 


GENITIVE 


MEANING 


PROPOSER 


Androm'-eda 

Androm'-edae 

Andromeda 

Ptolemy 

Ant'-lia 

Ant'-liae 

Air-pump 

La  Caille 

A'-pus 

Ap'-odis 

Bird  of  para- 

Bayer 

dise 

Aqua'-rius 

Aqua'-rii 

Water  carrier 

Ptolemy 

A'-quila 

A'-quilae 

Eagle 

Ptolemy 

A'-ra 

A'-re 

Altar 

Ptolemy 

A'-ries 

Ari'-etis 

Ram 

Ptolemy 

Auri'-ga 

Auri'-gae 

Charioteer 

Ptolemy 

Boo'-tes 

Boo'-tis 

Bootes 

Ptolemy 

Cae'-lum 

Cse'-li 

Chisel 

La  Caille 

Camelopar'- 

Camelopar'- 

Giraffe 

Hevelius  or 

dalis 

dalis 

Bartschius 

Can'-cer 

Can'-cri 

Crab 

Ptolemy 

Ca'-nes 

Ca'-num 

Hunting  dogs 

Hevelius 

Venat'-ici 

Venatico'- 

rum 

HISTORY  OF  THE  CONSTELLATIONS 


NAME 

GENITIVE 

MEANING 

PROPOSER 

Caf-nis 

Ca'-nis 

Greater  dog 

Ptolemy 

Ma'-jor 

Majo'-ris 

Ca'-nis 

Ca'-nis 

Lesser  dog 

Ptolemy 

Mi'-nor 

Mino'-ris 

Capricor'-nus 

Capricorf-ni 

Goat 

Ptolemy 

Cari'-na 

Cari'-nse 

Keel 

La  Caille 

Cassiope'-ia 

Cassiope'-iae 

Cassiopeia 

Ptolemy 

Centau'-rus 

Centau'-ri 

Centaur 

Ptolemy 

Ce'-pheus 

Ce'-phei 

Cepheus 

Ptolemy 

Ce'-tus 

Ce'-ti 

Whale 

Ptolemy 

Chamse'-leon 

Chamaelon'- 

Chameleon 

Bayer 

tis 

Cir'-cinus 

Cir'-cini 

Compasses 

La  Caille 

Colum'-ba 

Colum'-bae 

Dove 

Royer  or 

Bartschius 

Co'-ma 

Co'-mae 

Berenice's 

Tycho  Brahe 

Bereni'-ces 

Bereni'-ces 

hair 

or 

Eratosthenes 

Coro'-na 

Coro'-nse 

Southern 

Ptolemy 

Austra'-lis 

Austra'-lis 

crown 

Coro'-na 

Coro'-nae 

Northern 

Ptolemy 

Borea'-lis 

Borea'-lis 

crown 

Cor'-vus 

Cor'-vi 

Crow 

Ptolemy 

Cra'-ter 

Crate'-ris 

Cup 

Ptolemy 

Crux 

Cru'-cis 

Cross 

Royer 

Cygf-nus 

Cyg'-ni 

Swan 

Ptolemy 

Delphif-nus 

Delphi'-ni 

Dolphin 

Ptolemy 

Dora'-do 

Dora'-dus 

Sword-fish 

Bayer 

Dra'-co 

Draco'-nis 

Dragon 

Ptolemy 

Equu'-leus 

Equu'-lei 

Little  horse 

Ptolemy 

HOW  TO   IDENTIFY  THE   STARS 


NAME 

GENITIVE 

MEANING 

PROPOSER 

Erid'-anus 

Erid'-ani 

The  river 

Ptolemy 

For'-nax 

Forna'-cis 

Furnace 

La  Cailie 

Gem'-ini 

Gemino'-rum 

Twins 

Ptolemy 

Grus 

Gru'-is 

Crane 

Bayer 

Her'-cules 

Her'-culis 

Hercules 

Ptolemy 

Horolo'-gium 

Horolo'-gii 

Clock 

La  Cailie 

Hy'-dra 

Hy'-drae 

Snake 

Ptolemy 

Hy'-drus 

Hy'-dri 

Water  snake 

Bayer 

In'-dus 

In'-di 

Indian 

Bayer 

Lacer'-ta 

Lacer'-tae 

Lizard 

Hevelius 

Le'-o 

Leo'-nis 

Lion 

Ptolemy 

Le'-o  Mi'-nor 

Leof-nis 

Lesser  lion 

Hevelius 

Mino'-ris 

Le'-pus 

Lep'-oris 

Hare 

Ptolemy 

Li'-bra 

Li'-brae 

Balance 

Ptolemy 

Lu'-pus 

Lu'-pi 

Wolf 

Ptolemy 

Lynx 

Lyn'-cis 

,Lynx 

Hevelius 

Ly'-ra 

Ly'-rse 

Harp 

Ptolemy 

Ma'-lus 

Ma'-li 

Mast 

La  Cailie 

Men'-sa 

Men'-sae 

Table 

La  Cailie 

Microsco'- 

Microscof-pii 

Microscope 

La  Cailie 

pium 

Monoc'-eros 

Monocero'-tis 

Unicom 

Hevelius  or 

Bartschius 

Mus'-ca 

Mus'-cse 

Fly 

Bayer 

Nor'-ma 

Nor'-mae 

Rule 

La  Cailie 

Oc'-tans 

Octan'-tis 

Octant 

La  Cailie 

Ophiu'-chus 

Ophiu'-chi 

Serpent 

Ptolemy 

carrier 

Orir-on 

Orio'-nis 

Orion 

Ptolemy 

HISTORY   OF   THE  CONSTELLATIONS 


NAME 

GENITIVE 

MEANING 

PROPOSER 

Pa'-vo 

Pavo'-nis 

Peacock 

Bayer 

Peg'-asus 

Peg'-asi 

Winged  horse 

Ptolemy 

Per'-seus 

Per'-sei 

Perseus 

Ptolemy 

Phoe'-nix 

Phoeni'-cis 

Phoenix 

Bayer 

Pic'-tor 

Picto'-ris 

Painter 

La  Caille 

Pis'-ces 

Pis'-cium 

Fishes 

Ptolemy 

Pis'-cis 

Pis'-cis 

Southern 

Ptolemy 

Austra'-lis 

Austra'-lis 

fish 

Pup'-pis 

Pup'-pis 

Stern 

La  Caille 

Retic'-ulum 

Retic'-uli 

Net 

La  Caille 

Sagit'-ta 

Sagit'-tae 

Arrow 

Ptolemy 

Sagitta'-rius 

Sagitta'-rii 

Archer 

Ptolemy 

Scor'-pius 

Scor'-pii 

Scorpion 

Ptolemy 

Sculp'-tor 

Sculpto'-ris 

Sculptor 

La  Caille 

Scu'-tum 

Scu'-ti 

Shield 

Hevelius 

Ser'-pens 

Serpen'-tis 

Serpent 

Ptolemy 

Sex'-tans 

Sextan'-tis 

Sextant 

Hevelius 

Tau'-rus 

Tau'-ri 

Bull 

Ptolemy 

Telesco'-pium 

Telesco'-pii 

Telescope 

La  Caille 

Trian'-gulum 

Trian'-guli 

Triangle 

Ptolemy 

Trian'-gulum 

Trian'-guli 

Southern 

Bayer 

Austra'-le 

Austra'-lis 

triangle 

Tuca'-na 

Tuca'-nse 

American 

Bayer 

TTr'-si 

Ur'-sae 

goose 

{J  1       ocl 

Ma'-jor 

Majo'-ris 

Greater  bear 

Ptolemy 

Ur'-sa 

Ur'-sae 

Lesser  bear 

Ptolemy 

Mi'-nor 

Mino'-ris 

Ve'-la 

Velo'-rum 

Sails 

La  Caille 

Vir'-go 

Vir'-ginis 

Virgin 

Ptolemy 

Vo'-lans 

Volan'-tis 

Flying  (fish) 

Bayer 

Vulpec'-ula 

Vulpec'-ulae 

Fox 

Hevelius 

io  HOW  TO   IDENTIFY  THE   STARS 

It  will  be  seen  that  there  are  three  kinds  of 
names  used;  names  of  animals,  names  bor- 
rowed from  mythology,  and  names  of  pieces 
of  apparatus. 

When  and  where  the  constellations  were 
originally  designed  are  questions  which  have 
received  a  great  deal  of  attention  and  study. 
This  subject  can  be  merely  sketched  in  out- 
line here.  The  list  of  48  constellations  given 
by  Ptolemy  was  by  no  means  original  with 
him,  but  was  simply  a  slight  revision  of  an 
earlier  list  by  Hipparchus,  date  about  140  B.C. 
And  even  before  his  time  a  fairly  full  descrip- 
tion of  the  constellations  can  be  found  in  the 
poem  of  Aratus  of  Soli,  date  about  280  B.C. 
But  this  was  simply  a  versification  of  an 
earlier  astronomical  work  by  Eudoxus  in  370 
B.C.,  and  this  in  turn,  as  we  now  know,  was 
not  based  on  observations  made  by  the  Greeks, 
but  on  astronomical  information  that  was  at 
that  time  at  least  two  thousand  years  old. 
There  are  three  sources  of  information  as  to 
the  origin  of  the  constellations:  first,  the  in- 
ternal evidence  from  the  constellations  them- 
selves ;  secondly,  the  documentary  evidence  in 


HISTORY   OF   THE   CONSTELLATIONS          n 

the  form  of  references  in  the  early  writings; 
thirdly,  the  inscriptions  on  monuments,  tablets, 
coins,  etc.,  which  are  continually  being  dis- 
covered. The  originators  of  the  constellations 
naturally  portrayed  the  things  with  which  they 
were  familiar.  The  elephant,  camel,  tiger,  and 
crocodile  are  not  represented.  This  would 
exclude  India  and  Egypt  as  possible  places 
of  origin.  The  portion  of  the  sky  left  un- 
mapped shows  the  portion  of  the  sky  not 
visible  to  them.  They  must  thus  have  lived 
in  about  38°  north  latitude.  In  short,  all  lines 
of  evidence  show  that  the  constellations  prob- 
ably originated  in  the  Euphrates  valley,  and 
were  practically  complete  as  early  as  3000  B.C. 
What  we  have  is  thus  the  Latin  form  of  a 
Greek  digest  of  very  early  information.  For 
further  information  about  the  origin  of  the 
constellations,  see — 

BROWN,  Primitive  Constellations;  Williams  and  Nor- 
gate,  London,  1899. 

LOCKYER,  The  Dawn  of  Astronomy ;  The  Macmillan 
Company,  1894. 

MAUNDER,  Astronomy  without  a  Telescope,  Chapter  I ; 
"Knowledge"  Office,  London,  1902. 

MAUNDER,  The  Oldest  Picture-book  of  All;  The  Nine- 
teenth Century  Magazine,  September,  1900. 


III.      THE     METHODS     OF     DESIGNATING 
A   STAR 

THE  oldest,  but  now  obsolete,  method  of 
designating  a  particular  star  was  to  describe 
its  position  in  the  constellation.  The  portion 
of  the  sky  belonging  to  a  certain  constellation 
was  supposed  to  be  covered  by  a  representa- 
tion or  picture  of  the  thing  after  which  the 
constellation  was  named.  Thus  a  star  might 
be  described  as  located  "in  the  head  of  Her- 
cules" or  "in  the  right  knee  of  Bootes"  or 
"in  the  horn  of  the  bull."  Many  star  charts 
still  give  those  old  pictures  in  connection 
with  the  constellations. 

There  are  four  modern  methods  of  designat- 
ing a  star,  (i)  By  name.  Hundreds  of  stars 
have  received  individual  names,  but  less  than 
a  hundred  of  these  are  now  in  general  use. 
They  are  usually  of  Latin,  Greek,  or  Arabic 
origin,  and  are  either  proper  names  or  de- 
scribe position.  For  example:  Regulus,  Spica, 

12 


THE  METHODS  OF  DESIGNATING  A  STAR       13 

Aldebaran.  (2)  By  means  of  a  letter.  In  1603 
Bayer  introduced  the  system  of  designating 
the  stars  in  a  constellation  by  means  of  the 
letters  in  the  Greek  alphabet.  These  are,  in 
order : — 


a  alpha 

77  eta 

^  nu 

T  tau 

£  beta 

6  theta 

f  xi 

v  upsilon 

y  gamma 

i  iota 

o  omicron 

<f>  phi 

8  delta 

K  kappa 

•7T  pi 

X  chi 

e  epsilon 

X  lambda 

/>  rho 

t/f  psi 

£  zeta 

p,  mu 

cr  sigma 

a)  omega 

The  stars  were  usually  lettered  in  the  order  of 
brightness,  a  being  the  brightest  star,  ft  the 
next  brightest,  and  so  on.  When  the  letters 
of  the  Greek  alphabet  were  exhausted,  the 
Roman  letters  were  used.  In  a  few  instances 
the  stars  were  lettered  in  order  of  position 
instead  of  brightness.  The  Latin  genitive,  of 
the  constellation  name  always  follows  the 
Greek  or  Roman  letter.  For  example: 
a  Lyrae,  ft  Geminorum,  g  Ursae  Majoris. 
(3)  By  number.  About  1 700  Flamsteed  intro- 
duced the  custom  of  numbering  the  stars  in 
a  constellation.  This  applies  usually  to  the 


I4  HOW   TO   IDENTIFY  THE   STARS 

fainter  stars  which  had  not  been  lettered,  and 
they  were  numbered  in  order  of  position  from 
west  to  east.  For  example:  61  Cygni,  50 
Cassiopeiae.  (4)  By  catalogue  number.  In 
the  case  of  some  faint  stars  visible  to  the 
naked  eye,  and  nearly  all  stars  visible  in  a 
telescope  only,  the  star  is  designated  as  having 
a  certain  number  in  a  certain  catalogue.  It 
is  usually  the  first  catalogue  in  which  it  oc- 
curred or  some  very  well  known  comprehen- 
sive catalogue.  For  example:  Groombridge 
966,  B.A.C  4536. 

The  last  three  of  the  four  modern  methods 
seldom  overlap  at  present.  The  brighter  stars 
are  usually  lettered.  Those  which  are  fainter, 
but  still  visible  to  the  naked  eye,  are  usually 
numbered,  while  telescopic  stars  are  referred 
to  simply  by  catalogue  and  number.  If  a  star 
has  a  proper  name,  this  is  usually  given  in 
addition  to  the  Bayer  letter. 


IV.     STAR    MAGNITUDES 

THE  term  "  magnitude "  when  applied  to  a 
star  refers  simply  to  its  brightness  and  not 
to  its  volume  or  mass.  Ptolemy  arbitrarily 
graded  the  stars  visible  to  the  naked  eye  into 
six  classes  or  magnitudes,  the  sixth  being  the 
faintest  and  the  first  the  brightest.  The 
reason  for  having  six  magnitudes  rather  than 
more  is  not  known,  unless  it  is  because  the 
eye  without  the  help  of  instruments  is  unable 
to  make  finer  distinctions.  After  the  tele- 
scope was  invented,  the  number  of  magni- 
tudes had  to  be  increased  so  as  to  include 
these  faint  telescopic  stars,  but  there  was  no 
uniformity  among  different  observers  in  ex- 
tending the  system.  As  the  result,  the  mag- 
nitude of  a  faint  star,  as  determined  by  differ- 
ent observers,  might  differ  by  even  two  or 
three.  As  measurements  became  more  exact, 
it  also  became  desirable  to  subdivide  magni- 
tudes. 

'5 


16  HOW  TO  IDENTIFY  THE   STARS 

It  had  been  noticed  for  some  time  that, 
roughly  speaking,  a  star  of  the  first  magnitude 
was  about  one  hundred  times  as  bright  as  a 
star  of  the  sixth.  In  1850,  Pogson  proposed 
to  make  the  Vioo,  or  2.512,  the  uniform  ratio 
between  successive  magnitudes. 

Thus,  <$!  =  v'loo  62,  where  6t  is  the  bright- 
ness of  a  first  magnitude  star  and  £a  that  of  a 
second. 

Similarly,  bz  =  -N/IOO  6B9 

68  =  -v'Too  £4  etc. 

From  these  6i= 

or  ^- 

or  t9= 

Thus,  in  general,  bm  = 


Transposing  this,  -r  =  (Vioo)" 


logio  -^  =  0.4  (»-«). 

This  formula  put  into  words  is:    the  logarithm 
of  the  ratio  of  brightness  equals  four  tenths  of 


STAR   MAGNITUDES  17 

the  difference  in  magnitude.  By  means  of  this 
formula,  if  the  magnitudes  of  two  stars  are  given, 
the  ratio  of  brightness  may  be  computed,  and  if 
the  ratio  of  brightness  and  the  magnitude  of 
one  star  is  given,  the  magnitude  of  the  other 
may  be  computed. 

EXAMPLE  i.  If  the  magnitude  of  Mizar 
(£  Ursae  Majoris)  is  2.4  and  the  magnitude  of 
Alkor  (g  Ursae  Majoris)  is  4.0,  find  their  ratio 
of  brightness. 

Iog10  ratio  =  0.4(4.0  —  2.4)  =  o.4( i  .6)  =  0.64. 
Ratio  of  brightness  =  4.37. 

EXAMPLE  2.  If  a  star  is  30  times  as  bright  as 
Polaris  (a  Ursae  Minoris),  magnitude  2.1,  find  its 

magnitude. 

Iog103o  =  0.4(2.1-^), 

1.477  =  0.84-0.4.*, 
0.4^=  -0.637, 
x=  -1.59- 

The  magnitude  is  —  1.59,  and  this  is  the  mag- 
nitude of  Sirius  (a  Canis  Majoris). 

This  definite  system  of  star  magnitudes  was 
gradually  adopted,  and  now  all  star  magnitudes 
are  expressed  in  it.  Some  star  must  be  con- 


i8  HOW  TO   IDENTIFY  THE   STARS 

sidered  to  be  fundamental,  that  is,  to  have  a 
definite  unchanging  magnitude,  and  the  mag- 
nitudes of  the  other  stars  must  be  determined 
in  terms  of  its  magnitude.  Polaris  (a  Ursae 
Minoris)  is  usually  taken  as  the  fundamental 
star.  By  means  of  photometers  all  other 
stars  are  compared  with  it,  either  directly  or 
indirectly,  and  the  ratio  of  brightness,  and 
thus  the  magnitude,  determined.  The  work 
of  the  Harvard  College  Observatory  in  this 
connection  has  been  particularly  noteworthy. 
Here  the  actual  standard  is  not  Polaris  but  the 
mean  magnitude  of  one  hundred  circumpolar 
stars  of  about  the  fifth  magnitude. 

In  this  system  of  magnitudes,  the  naked 
eye  can  perceive  stars  of  about  the  sixth  mag- 
nitude if  the  air  is  clear  and  free  from  haze. 
One  disadvantage  of  the  system  is  the  fact 
that  there  are  stars  brighter  than  the  first 
magnitude.  A  star  2.51  times  as  bright  as 
one  of  the  first  magnitude  would  be  of  the 
o  magnitude.  A  star  2.51  times  as  bright  as 
that  would  be  of  the  —  i  magnitude.  Thus 
for  a  very  bright  object  a  negative  magnitude 
must  be  used.  There  is  one  star  which  has 


STAR   MAGNITUDES  19 

a  negative  magnitude,  Sirius  (a  Canis  Majoris) 
—  1.6.  On  the  same  scale  the  sun  would  have 
a  magnitude  of  —26.3. 

The  magnitudes  of  stars  remain  remarkably 
constant.  There  are  only  about  500  stars  in 
connection  with  which  a  variation  in  magni- 
tude has  been  detected,  and  only  about  50  of 
these  are  visible  to  the  naked  eye.  The 
change  in  magnitude  may  be  a  steady  change 
in  one  direction,  an  irregular  fluctuation,  or  a 
periodic  variation.  If  the  fluctuation  is  irreg- 
ular, only  the  limits  can  be  stated.  If  the 
variation  is  periodic,  such  facts  as  the  limits 
of  the  variation  and  the  period  may  be  deter- 
mined. 


V.     STAR   COLORS 

MOST  of  the  stars  appear  to  us  as  white, 
although  in  a  few  cases  the  star  appears  to 
be  tinged  with  color.  The  following  list  prob- 
ably includes  the  various  colors  as  they  appear 
to  the  naked  eye:  greenish  white,  bluish  white, 
white,  yellowish  white,  orange-white,  reddish 
white.  Stars  are  sometimes  said  to  be  yellow, 
orange,  or  red,  but  in  every  case  the  white  pre- 
dominates to  such  an  extent  that  it  is  really 
only  a  tinge  of  the  color  in  question  that  is 
perceived. 

As  seen  through  the  telescope  all  the  spec- 
trum colors  may  be  noticed,  but  in  every  case 
they  are  strongly  mixed  with  white. 

The  causes  of  these  differences  in  color  are 
differences  in  temperature  and  chemical  corn- 
position. 


VI.     THE   NUMBER   OF   THE   STARS 

THE  opinion  is  often  expressed  that  the  stars 
appear  almost  countless  in  number.  As  a  mat- 
ter of  fact  the  total  number  visible  to  the  naked 
eye  is  only  about  6,000.  Only  one-half  of  these 
are  visible  at  any  one  time,  and  a  small  amount 
of  haze  greatly  reduces  the  number  that  is 
visible,  particularly  near  the  horizon.  Thus 
on  a  night  which  would  be  considered  clear 
only  about  2,000  stars  are  visible.  As  was 
said  before,  the  sixth  magnitude  is  usually 
considered  the  limit  of  visibility  to  the  naked 
eye.  The  following  table  gives  the  number 
of  stars  between  each  magnitude.  The  sec- 
ond line  of  the  table  gives  the  values  of  4  x  3"", 
where  m  is  the  magnitude.  The  agreement  is 
remarkably  close.  Expressed  in  words,  the  law 
would  be  that  there  are  about  three  times  as 
many  stars  in  each  magnitude  as  in  the  pre- 
ceding magnitude. 

21 


HOW  TO   IDENTIFY  THE   STARS 


Magnitude  o  i  2 
Number  of  stars  1 1  28 
4X3m  12  36 


3 
103 

108 


4 
321 

324 


5 

IO2O 
972 


6 

2843 
2916 


The  following  list  of  the  twenty  brightest 
stars  gives  the  proper  name,  the  Bayer  letter, 
the  magnitude,  and  the  color.  The  word  "  (in- 
visible)" indicates  that  the  star  is  never  visible 
in  the  United  States: — 

THE  TWENTY  BRIGHTEST  STARS 


Bluish  white 
0.2  Orange 

Yellow 
0.3  White 

0.3  White  (invisible) 
0.4  Bluish  white  (invisible) 

White 

0.6  White  (invisible) 
0.9  Red 
0.9  Yellow 
0.9  White  (invisible) 

Red 

Red 

1.2  Orange 
White 

1.3  Bluish  white  (invisible) 
1.3  Orange 

1.3  White 
White 


Sirius 

a  Canis  Majoris  — 

i, 

Vega 

a  Lyrae 

0, 

Arcturus 

a  Bootis 

0. 

Capella 

a  Aurigae 

0, 

Rigel 

ft  Orionis 

o, 

Canopus 

a  Argus 

o. 
o, 

Procyon 

a  Canis  Minoris 

o, 

Achernar 

a  Eridani 

0, 

Betelgeuse 

a  Orionis 

o, 

Altair 

a  Aquilae 

o. 

ft  Centauri 

o. 

Aldebaran 

a  Tauri 

I, 

Antares 

a  Scorpii 

I. 

Pollux 

ft  Geminorum 

I. 

Spica 

a  Virginis 

I. 



a  Crucis 

I. 

Fomalhaut 

a  Piscis  Australis 

I. 

Regulus 

a  Leonis 

I. 

Deneb 

a  Cygni 

I, 

VII.     THE    METHOD    OF    LOCATING    THE 
STARS    AND    CONSTELLATIONS 

THE  method  of  locating  the  stars  and  con- 
stellations here  advocated  is  by  means  of  the 
so-called  constellation  tracings.  Most  of  the 
conspicuous  constellations  contain  bright  stars 
which,  when  connected  by  lines,  form  figures, 
such  as  a  triangle,  square,  W,  sickle,  etc., 
which  are  easily  remembered  and  quickly  rec- 
ognized. After  these  tracings  have  once  been 
learned  and  noticed,  as  soon  as  the  eye  falls 
upon  that  part  of  the  sky,  it  instinctively  runs 
through  the  tracing,  and  the  constellation  is 
thus  recognized  and  its  stars  identified.  For 
convenience  in  locating  them,  the  88  constel- 
lations have  been  divided  into  four  groups. 
The  first  group  consists  of  28  conspicuous 
constellations  with  tracings.  The  second  group 
contains  the  five  constellations  which  are  chiefly 
conspicuous  on  account  of  a  single  very  bright 
star.  The  third  group  of  19  comprises  the 

23 


24  HOW  TO   IDENTIFY  THE   STARS 

inconspicuous  constellations,  while  the  fourth 
group  contains  the  36  constellations  which 
are  too  far  south  to  be  seen  at  all  or  well  seen 
from  the  United  States.  The  following  table 
in  four  parts  gives  these  four  groups  of  con- 
stellations:— 

THE  88   CONSTELLATIONS   DIVIDED   INTO   FOUR 
GROUPS 

I.  THE  28  CONSPICUOUS  CONSTELLATIONS  WITH  TRACINGS 


ANDROMEDA 

AQUILA 

ARIES 

AURIGA 

CASSIOPEIA 


(triangle) 

(pentagon) 

(W) 


LYRA      (triangle  and  parallelogram) 

OPHIUCHUS 

(parallelogram) 
(square) 


CORONA  BOREALIS  (semicircle) 

CORVUS 

CYGNUS  (cross) 

DELPHINUS 

DRACO 

GEMINI 

HERCULES 

LEO  (sickle  and  triangle) 

LIBRA 


ORION 

PEGASUS 

PERSEUS 

SAGITTA 

SAGITTARIUS 

SCORPIUS 

SERPENS 

TAURUS 

TRIANGULUM 

URSA  MAJOR 

URSA  MINOR 

VIRGO 


(arrow) 
(sickle) 

(wedge) 

(triangle) 

(big  dipper) 

(little  dipper) 


II.  THE  5  CONSTELLATIONS  WITH  A  SINGLE  VERY  BRIGHT 
STAR 

BOOTES  CANIS  MAJOR 

CANES  VENATICI  CANIS  MINOR 

1*ISCIS   AUSTRALIS 


LOCATING  THE  STARS  AND  CONSTELLATIONS     25 

III.  THE  19  INCONSPICUOUS  CONSTELLATIONS 

AQUARIUS  ERIDANUS 

CAMELOPARDALIS  HYDRA 

CANCER  LACERTA 

CAPRICORNUS  LEO  MINOR 

CEPHEUS  LYNX 

CETUS  MONOCEROS 

COMA  BERENICES  PISCES 

CRATER  SCUTUM 

EQUULEUS  SEXTANS 
VULPECULA 

IV.  THE  36  SOUTHERN  CONSTELLATIONS 

ANTLIA  LUPUS 

APUS  MALUS 

ARA  MENSA 

CELUM  MlCROSCOPIUM 

CARINA  MUSCA 

CENTAURUS  NORMA 

CHAMELEON  OCTANS 

CIRCINUS  PAVO 

COLUMBA  PHCENIX 

CORONA  AUSTRALIS  PICTOR 

CRUX  PUPPIS 

DORADO  RETICULUM 

FORNAX  SCULPTOR 

GRUS  TELESCOPIUM 

HOROLOGIUM  TRIANGULUM  Aus. 

HYDRUS  TUCANA 

INDUS  VELA 

LEPUS  VOLANS 


26  HOW  TO   IDENTIFY  THE   STARS 

Charts  I.  to  IV.  show  the  position  of  the 
constellations  at  9  P.M.  during  January,  April, 
July,  and  October.  During  a  following  month 
they  would  show  the  position  two  hours  earlier, 
and  during  a  preceding  month  two  hours  later. 
That  is,  stars  come  into  the  same  position  two 
hours  earlier  after  the  lapse  of  a  month.  The 
28  conspicuous  constellations  and  the  five  with 
single  very  bright  stars  are  printed  in  small 
capitals,  while  the  inconspicuous  constellations 
are  printed  in  small  letters.  In  order  to  match 
the  sky,  the  chart  is  supposed  to  be  held  over 
the  head  of  an  observer  facing  south.  Thus 
for  a  convenient  hour  of  the  evening,  the  posi- 
tion of  the  constellations  is  given  for  every 
month  in  the  year.  In  order  to  get  the  posi- 
tion at  any  other  hour  of  the  evening,  only  the 
apparent  diurnal  rotation  of  the  heavens  need 
be  taken  account  of. 

Figures  i  to  24  give  the  tracings  and  infor- 
mation about  the  28  conspicuous  constellations. 
Andromeda  and  Perseus,  Aries  and  Triangu- 
lum,  Libra  and  Scorpius,  Ophiuchus  and  Ser- 
pens,  are  represented  by  one  figure  for  each 
pair.  The  faint  lines  represent  the  tracings. 


LOCATING  THE  STARS  AND  CONSTELLATIONS     27 

The  arrow  points  to  the  north  pole  of  the 
heavens,  and  thus  indicates  for  a  constellation 
in  any  position  how  the  tracing  must  be  held 
to  match  the  sky.  Three  symbols  are  used  to 
represent  the  stars,  depending  upon  their  mag- 
nitude: -f-  for  stars  having  a  magnitude  of 
1.4  or  brighter;  •  for  stars  having  a  magni- 
tude between  1.5  and  3.4  inclusive;  •  for  stars 
having  a  magnitude  of  3.5  or  less.  The  desig- 
nation of  the  star  and  its  exact  magnitude 
according  to  the  measurements  made  at  the 
Harvard  College  Observatory  are  stated.  The 
proper  name  of  the  star  is  also  given,  and  its 
color  if  not  white,  and,  if  variable,  the  limits 
of  the  variation  and  the  period  if  periodic.  At 
the  bottom  of  each  figure  the  right  ascension 
and  declination  of  the  center  of  each  constella- 
tion are  indicated.1 

1  Right  ascension  and  declination  are  the  coordinates  in  the 
so-called  equator  system  of  coordinates.  The  fundamental  points 
of  this  system  are  the  poles  of  the  celestial  sphere,  that  is,  the 
points  of  no  diurnal  motion  on  the  celestial  sphere.  These  are 
the  points  where  the  earth's  axis  produced  cuts  the  celestial 
sphere.  The  north  pole  is  located  near  Polaris  (a  Ursae  Mi- 
noris).  The  celestial  equator  is  a  great  circle  90°  from  the  pole. 
It  is  the  great  circle  in  which  the  plane  of  the  earth's  equator 
cuts  the  celestial  sphere.  The  equator  runs  through  the  con- 


28  HOW  TO   IDENTIFY  THE   STARS 

The  facts  concerning  the  five  constellations 
with  a  single  very  bright  star  are:  — 

Bootes  —  a;  name,  Arcturus;  magnitude,  0.2;  color, 
orange-white. 

Canes  Venatici  —  a;  name,  Cor  Caroli;  magnitude,  3.3; 
color,  white. 

Canis  Major — a ;  name,  Sirius ;  magnitude,  — 1.6 ;  color, 
bluish  white. 

Canis  Minor  —  a ;  name,  Procyon ;  magnitude,  0.5  ; 
color,  bluish  white,  (ft  Canis  Minoris  has  a  magnitude 
of  3.1  and  is  fairly  conspicuous.  The  constellation  could 
perhaps  have  been  represented  by  these  two  stars  better 
than  by  a  single  star.) 

Piscis  Australis — a;  name,  Fomalhaut;  magnitude,  1.3; 
color,  orange-white. 

Of  the.  19  inconspicuous  constellations  Can- 
cer and  Cepheus  are  perhaps  the  most  easily 
recognized.  There  are  two  stars  in  Cepheus 

stellations  of  Pisces,  Cetus,  Taurus,  Orion,  Monoceros,  Hydra, 
Sextans,  Leo,  Virgo,  Serpens,  Ophiuchus,  Aquila,  Aquarius. 
The  great  circles  drawn  through  the  poles  and  perpendicular  to 
the  equator  are  called  hour  circles.  The  starting  point  or  origin 
of  coordinates  is  the  vernal  equinox,  the  point  where  the  sun 
crosses  the  equator  on  March  21.  It  is  located  in  the  constella- 
tion of  Pisces.  Declination  is  angular  distance  north  or  south 
of  the  equator ;  plus  when  north  and  minus  when  south.  Right 
ascension  is  the  portion  of  the  equator  between  the  vernal  equi- 
nox and  the  hour  circle  through  the  point  in  question.  It  is 
usually  expressed  in  time  and  runs  from  o  to  24  hours. 


LOCATING  THE  STARS  AND  CONSTELLATIONS     29 

which  catch  the  eye  first  and  they  are  quite  a 
little  brighter  than  those  near  them.  These 
are  a  (magnitude  2.6)  and  fi  (magnitude  3.3). 
Cancer  is  noticeable  on  account  of  the  three 
stars  quite  close  together  which  form  a  little 
equilateral  triangle. 

The  best  method  of  building  up  an  acquaint- 
ance with  the  stars  and  constellations  from  the 
material  here  given  can  only  be  suggested. 
Most  people  know  at  least  two  or  three  con- 
stellations. If  that  is  the  case,  the  best  method 
of  procedure  is  to  study  first  the  constellations 
which  surround  those  which  are  already  known. 
Notice  the  tracing,  determine  where  the  con- 
stellation is  with  reference  to  those  already 
known,  and  then  try  to  pick  it  out  among 
the  stars.  In  this  way  all  of  the  constellations 
will  become  gradually  known.  If  no  constella- 
tions at  all  are  already  familiar  to  the  observer, 
start  with  those  which  are  by  far  the  most  con- 
spicuous. These  are  probably  Aries,  Auriga, 
Cassiopeia,  Leo,  Lyra,  Orion,  Pegasus,  Scor- 
pius,  Taurus,  Ursa  Major.  Determine  from 
the  charts  where  the  constellation  is  located, 
observe  carefully  the  tracing,  noting  particu- 


30  HOW  TO   IDENTIFY  THE   STARS 

larly  the  magnitudes  of  the  stars,  and  then 
persevere  until  the  constellation  is  recognized. 

For  example,  if  the  attempt  is  t6  be  made 
to  find  the  constellation  of  Taurus,  fix  firmly 
in  mind  before  going  out  to  observe  the  sky 
that  the  tracing  is  a  V,  that  all  of  the  stars  but 
one  are  of  about  the  same  magnitude  and  only 
moderately  bright,  and  that  the  one  bright 
star  is  of  the  first  magnitude  and  reddish  in 
color.  As  these  facts  are  sometimes  forgotten 
while  observing  the  sky,  it  is  often  convenient 
to  take  with  one  the  tracings  and  a  pocket 
electric  lamp  for  illuminating  them. 

When  a  beginning  has  once  been  made, 
progress  is  usually  easy.  A  single  hour's  in- 
struction by  one  familiar  with  the  stars  and 
constellations  is  sufficient  to  give  a  considera- 
ble amount  of  information  to  a  beginner,  par- 
ticularly if  the  charts  and  tracings  have  been 
carefully  studied  previously. 

Another  method  advocated  by  some  for 
building  up  an  acquaintance  with  the  stars  and 
constellations  is  to  start  with  the  fifteen  bright- 
est stars.  The  chief  facts  about  these  stars 
have  been  given  in  a  previous  table.  Find 


LOCATING  THE  STARS  AND  CONSTELLATIONS     31 

out,  by  looking  up  the  constellations  on  the 
charts,  how  many  of  these  are  visible  at  the 
desired  time  of  observation  and  in  what  part 
of  the  sky  they  are  located.  Then  persevere 
as  before  until  these  have  been  recognized, 
and  from  these  as  known  points  build  up  an 
acquaintance  with  the  surrounding  stars  and 
constellations.  This  method  of  starting  with 
the  bright  stars  can  be  used  to  the  best  ad- 
vantage when  the  moon  is  from  three  to  seven 
days  old.  The  light  of  the  moon  pales  out 
the  fainter  stars,  thus  making  the  bright  ones 
more  conspicuous.  A  perfectly  clear  moon- 
less night  is  not  the  best  time  to  begin  ob- 
servations, as  the  number  of  stars  visible  is 
confusing. 

Some  advocate  trying  to  locate  the  stars 
and  constellations  by  identifying  them  when 
rising  or  setting.  The  disadvantages  of  this 
method  are  that  the  horizon  is  always  more 
hazy  and  cloud-covered  than  the  rest  of  the 
sky,  and,  secondly,  that  it  confines  the  time 
of  observation  to  a  particular  hour  of  the 
night  and  is  impossible  at  some  times  of 
year. 


ja  HOW  TO   IDENTIFY  THE   STARS 

Any  attempt  to  locate  a  star  or  constellation 
by  giving  its  direction  and  distance  from  a 
known  point  will  be  no  more  successful  than 
to  notice  its  location  on  a  chart. 


VIII.      THE    METHOD    OF    FURTHER 
STUDY 

THE  charts,  figures,  and  information  given 
above  can  serve  only  as  a  guide  in  taking  the 
first  steps  in  learning  the  stars  and  constella- 
tions. Further  knowledge  is  both  useful  and 
pleasant,  and  to  gain  it  the  reader  must  be 
referred  to  the  numerous  books  bearing  on  the 
subject.  Some  of  these  books  will  be  indi- 
cated here. 

ALLEN,  Star-names  and  their  Meanings; 
G.  E.  Stechert,  1899,  is  a  veritable  mine  of 
information.  It  gives  the  meaning  of  the 
names  used  in  connection  with  the  stars  and 
constellations,  numerous  extracts  from  the  writ- 
ings where  these  names  were  used,  and  the 
more  important  facts  such  as  magnitude,  color, 
etc.,  about  the  chief  stars  in  each  constellation. 
It  is  a  compendium  of  information,  but  not  a 
book  to  be  read  through  as  a  whole. 

There  are  two  books,  MARTIN,  The 
Friendly  Stars;  Harper  and  Brothers,  1907, 

D  33 


34  HOW  TO  IDENTIFY  THE   STARS 

and  SERVISS,  Astronomy  with  the  Naked 
Eye;  Harper  and  Brothers,  1908,  which  at- 
tempt to  put  in  readable  and  attractive  form 
the  facts  concerning  the  stars  and  constella- 
tions. The  last-named  book  also  contains  star 
charts,  giving  the  position  of  all  stars  down  to 
the  sixth  magnitude.  These  are  the  two  books 
to  recommend  whenever  a  book  giving  a  popu* 
lar  presentation  of  the  subject  is  desired. 

Among  the  modern  up-to-date  star  atlases 
may  be  mentioned: — 

BALL,  A  Popular  Guide  to  the  Heavens;  George  Philip 
&  Son,  London,  1905. 

KLEIN,  Star  Atlas  ;  E.  &  J.  B.  Young  &  Co.,  New  York, 
1901. 

PECK,  The  Observer's  Atlas  of  the  Heavens;  Gall  & 
Inglis,  London,  1898. 

UPTON,  Star  Atlas;  Ginn  &  Company,  1896. 

MESSER,  Stern- Atlas  fur  Himmelsbeobachtungen  ;  K. 
L.  Ricker,  Leipzig,  1902. 

A  star  atlas  is  absolutely  essential  to  one  who 
desires  to  add  to  his  knowledge  of  the  stars 
and  constellations.  The  star  charts  in  these 
atlases  represent  all  the  constellations  with 
their  boundaries,  and  give  the  location  of  all 
stars  visible  to  the  naked  eye.  In  addition 


THE  METHOD  OF   FURTHER  STUDY  35 

much  information  is  given  concerning  star 
magnitudes,  double  stars,  variable  stars,  star 
colors,  etc.  The  meaning  of  the  names,  how- 
ever, and  the  historical  side  of  the  subject  are 
usually  not  treated.  If  it  is  desired  to  identify 
an  unknown  star,  the  best  method  is  to  esti- 
mate its  magnitude  carefully,  and  note  its  loca- 
tion with  reference  to  several  known  stars  or 
constellations.  A  chart  of  this  portion  of  the 
sky  may  then  be  consulted,  and  the  unknown 
star  can  usually  be  readily  identified  and  the 
constellation  to  which  it  belongs  determined. 
If  it  is  desired  to  locate  an  inconspicuous  star 
or  constellation,  the  best  method  is  to  note  on 
the  appropriate  chart  its  location  with  refer- 
ence to  several  easily  identified  stars  or  con- 
stellations. On  turning  to  the  sky  the  incon- 
spicuous object  can  usually  be  readily  located 
and  identified.  In  this  way,  by  means  of  star 
atlases,  one's  information  may  be  indefinitely 
extended. 

Such  atlases  as  ARGELANDER'S  Atlas 
des  Nordlichen  Gestirnten  Himmels  (2d  edi- 
tion by  Kiistner,  Bonn,  1899),  PETERS'S 
Celestial  Charts  (published  at  Canton,  N.  Y.), 


36  HOW  TO   IDENTIFY  THE   STARS 

and  the  Uranometria  Argentina  are  useful 
only  in  connection  with  the  telescope  when  it 
is  desired  to  identify  all  the  stars,  perhaps 
even  to  the  ninth  or  tenth  magnitude,  within 
a  very  small  area  such  as  the  field  of  view  of 
the  telescope. 

Lists  of  the  constellations,  the  stars  visible 
to  the  naked  eye,  colored  stars,  variable  stars, 
etc.,  can  also  be  found  in  CHAMBERS'S 
Handbook  of  Descriptive  and  Practical  As- 
tronomy (The  Clarendon  Press,  1890)  and 
VALENTINER,  Handworterbuch  der  As- 
tronomie  (Breslau,  1901). 

If  the  coordinates  of  a  star,  right  ascension, 
and  declination  are  desired,  they  may  be  found 
for  a  small  selected  list  of  stars  in  The  Ameri- 
can Ephemeris  and  Nautical  Almanac,  pub- 
lished each  year  at  Washington,  or  in  the  cor- 
responding year  books  of  the  English,  French, 
and  German  governments.  AMBRONN, 
Sternverzeichnis  (Julius  Springer,  Berlin,  1907) 
also  contains  the  coordinates  of  all  stars  (7796 
in  all)  which  are  above  the  6.5  star  magnitude. 
Such  information,  however,  is  desired  not  by 
the  observer  who  is  locating  an  object  by 


THE   METHOD   OF   FURTHER   STUDY  37 

means  of  the  stars,  but  by  the  computer  who 
is  reducing  the  observations. 

The  following  list  contains  other  valuable 
books  on  the  stars  and  constellations:  — 

BURRITT,  Atlas  designed  to  illustrate  the  Geography 
of  the  Heavens;  New  York,  1835. 

COTTAM,  Charts  of  the  Constellations;  London,  1889. 

DIEN,  Atlas  Celeste;  Paris,  1869. 

GORE,  Star  Groups;  Crosby  Lockwood  &  Sons,  Lon- 
don, 1891. 

HEIS,  Atlas  Ccelestis  Nouvus  ;  Cologne,  1872. 

HILL,  The  Stars  and  Constellations;  Funk  &  Wagnalls 
Company,  New  York,  1894. 

JEANS,  Handbook  for  Finding  the  Stars;  London,  1888. 

JOHNSTON,  School  Atlas  of  Astronomy  (revised  by 
Grant)  ;  G.  P.  Putnam's  Sons,  New  York. 

MAUNDER,  Astronomy  without  a  Telescope;  London, 
1902. 

PECK,  The  Constellations  and  how  to  find  them;  Gall 
&  Inglis,  London. 

PORTER,  The  Stars  in  Song  and  Legend;  Ginn  &  Com- 
pany, New  York,  1902. 

PROCTOR,  Half -hours  with  the  Stars;  G.  P.  Putnam's 
Sons,  1875. 

SERVISS,  Pleasures  of  the  Telescope;  D.  Appleton  & 
Company,  New  York,  1905. 

SERVISS,  Astronomy  with  an  Opera-glass;  D.  Apple- 
ton  &  Company,  New  York,  1906. 

YOUNG,  Uranography,  in  his  Elements  of  Astronomy; 
New  York,  1890. 


38  HOW  TO   IDENTIFY  THE   STARS 

The  star  atlases  of  Burritt,  Heis,  and  Dien 
are  particularly  interesting,  as  they  give  great 
prominence  to  the  constellation  figures,  as  was 
the  case  with  all  the  older  atlases. 


Printed  in  the  United  States  of  America. 


CHART    I. 


January  1st,  9  p.m 


Dec.  1st,  11  p.m. 
Feb.  1st,  7  p.m. 
March  1st,  5  p.n 


Cephene 

Laeerta 
Camelopardalie   CASSIOPEIA 

PEGASUS 
ANDROMEDA 


(zenith) 

0  PERSEUS 

AUR1GA  TRIANGULUJl 


CHART    II. 


April  1st,  9  p.m 


March  1st,  11  p.m. 
May  1st.  7  p.m. 


DRACO 

CORONA  TTRSA        Camelopardalis 

BOREALIS  MINOR 


July  1st,  9  p.m. 


CHART    III. 


N 


June  1st,  11  p.m. 
August  1st,  7  p.m. 


AURIGA* 


Lacerta 


CASSIOPEIA,    camelopardalis 

("0/e'  Lynx 


Cepheua 


'PEGASUS 


URSA  MIHOK 

URSA  MAJOR 


Crater i 


CHART    IV. 


October  1st,  9  p.m. 


Sept.  1st,  11  p.m. 
Nov.  1st,  7  p.m. 
Dec.  1st,  5  p.m. 


ANDROMEDA 


(Algol 

War.  2.3  to  3.5    3  d. 


FIG.  i 


FIG.  2 


FIG.  3 


FIG.  4 


FIG.  5 


FIG.  6 


FIG.  7 


FIG.  8 


FIG.  9 


FIG.  10 


GEMINI 


ft  Pollux    Or.W 

Var.  3.2  to  4.0    230  d. 


FIG.  ii 


FIG.  12 


FIG.  13 


SCORPIUS 


intares    RW 
161/,  h.  -26° 


FIG.  14 


FIG.  15 


FIG.  16 


FIG.  17 


FIG.  18 


FIG.  19 


FIG.  20 


FIG.  21 


FIG.  22 


FIG.  23 


FIG.  24 


UNIVERSITY  OF  CALIFORNIA  LIBRARY 
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